Looking for advice diagnosing large muzzle velocity spreads. This is the second powder test as the video camera failed to record shots on target on a previous test. From velocities on that previous test I was favouring 43.2. Therefore I loaded 6 sighters at 43.2. Again 43.2 looked like the spot.
BUT look at the 77 fps spread of the 7 shots at 43.2. (6 sighters and 1 in ladder) I haven’t been able to trim down my ES after months of refining. Different brass, primers, bullets(Sierra,Berger,Hornady) weights, techniques, etc.
I will list details of this test in case it may help someone spot any issues:
Tikka varmint 308, 24” barrel, 1-11 twist, bedded into MDT chassis.
Lapua brass, Varget, 175 TMK, CCI BR2.
Brass is annealed, FL sized with Redding S type with no bushing .002 bump, neck sized with Lee collet using torque wrench at 35 foot lbs. Trimmed, chamfered, brushed.
Powder is measured with a tuned RCBS 502 with camera that is proven repeatable and sensitive to one kernel of Varget.
Bullets seated with Forster micrometer die.
I don’t know where to go from here.
Thanks in advance.
BUT look at the 77 fps spread of the 7 shots at 43.2. (6 sighters and 1 in ladder) I haven’t been able to trim down my ES after months of refining. Different brass, primers, bullets(Sierra,Berger,Hornady) weights, techniques, etc.
I will list details of this test in case it may help someone spot any issues:
Tikka varmint 308, 24” barrel, 1-11 twist, bedded into MDT chassis.
Lapua brass, Varget, 175 TMK, CCI BR2.
Brass is annealed, FL sized with Redding S type with no bushing .002 bump, neck sized with Lee collet using torque wrench at 35 foot lbs. Trimmed, chamfered, brushed.
Powder is measured with a tuned RCBS 502 with camera that is proven repeatable and sensitive to one kernel of Varget.
Bullets seated with Forster micrometer die.
I don’t know where to go from here.
Thanks in advance.
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